ACE (angiotensin converting enzyme) inhibitors fall into the class of high blood pressure medicines (antihypertensives) used to treat high blood pressure (hypertension). Trandolopril, spiropril and perindopril are ACE inhibitors that can penetrate the blood-brain barrier.
Anatomical studies in animals and humans have shown that there are angiotensin type I receptors in the substantia nigra. People with Parkinson's disease have fewer angiotensin type 1 receptors in their brains. Angiotensin II stimulates the release of newly synthesized dopamine. In examining the relationship between angiotensin type I receptors and people with Parkinson’s disease, a double-blind, placebo-controlled, crossover study demonstrated that after a 4-week treatment period with perindopril (an ACE Inhibitor), “patients had a faster onset in their motor response to levodopa and a reduction in peak dyskinesia.”
Possible negative interactions with other medicines
Lower blood pressure
Reduced kidney function
Reduced number of white blood cells, which can lead to serious infections
Seven patients (six women and one man) with moderately severe Parkinson's disease (Hoen and Yahr scale 3) entered a double blind, placebo-controlled crossover study. The results confirmed the concept that an ACE inhibitor can improve the motor response to L-dopa in patients with Parkinson's disease. The drug also increased the proportion of the day spent in the 'on' state, and showed an improvement in the functional disability scale used.
162 people in Japan with mild to moderate Alzheimer's disease and high blood pressure were divided into three groups for a one-year study. Each group of trial participants received either a brain-penetrating ACE inhibitor, a non-brain-penetrating ACE inhibitor, or another type of blood pressure drug. Trial participants in the brain-penetrating ACE inhibitor groups received one of two drugs - perindopril or captopril. The study showed that those who were on a brain-penetrating ACE inhibitor showed less decline in memory than the other trial participants.
 Angiotensin-converting Enzyme (ACE) Inhibitors; Retrieved date: March 13, 2005
 A new approach to treating Parkinson's disease? ..Summarized by Robert W. Griffith, MD, January 30, 2001 (Reviewed: February 18, 2003)
 Potential Noncardiac, Nonrenal Uses of Angiotensin; from Medscape Pharmacotherapy, Retrieved date: March 13, 2005
 A new approach to treating Parkinson's disease? Summarized by Robert W. Griffith, MD
January 30, 2001 (Reviewed: February 18, 2003)
 Medical News Today; Blood Pressure Drugs May Slow Deterioration of Alzheimer's, 12 Oct 2004